abbreviation of "ounce," or "ounces," a unit of weight equal to one sixteenth of a pound or 28.350 grams in the avoirdupois weight system, and equal to one twelfth of a pound or 31.1051 grams in the apothecaries' weight and the troy weight systems.

oxygen in the form of molecules with three atoms, created by exposure of oxygen to electrical discharge or ultraviolet radiation, having a sharp smell, and being an effective oxidant for use in bleaching and sterilizing.

an atmospheric layer between ten and twenty miles above the earth that contains a substantial concentration of ozone, which absorbs ultraviolet radiation from space and prevents some heat loss from the earth; ozonosphere.